Improve JSDoc compliance and add automated checking

Created by: davemevans

This large PR has no functional changes, but makes the documentation more compliant with both the JSDoc3 standard, and the Google Closure standard.

Where it was missing I have tried to add type information etc.

I have also added JSDoc settings to the JSCS config so that any new documentation is automatically checked as it is added. I haven't put a great deal of though into the options, so am happy to change, add or remove options if anyone has any strong feelings.